The transfer of dikes, a nightmare for certain elected officials

With 550 km of so-called "state" dikes, the "levees", the Loire Valley is the region most affected by this transfer provided for in the "Maptam" law of 2014, which entrusted the management of aquatic environments and flood prevention (gemapi).

“We calculated that it would be necessary to invest at least 350 million euros over 20 years, just to have a normal level of protection of the dikes across the Loire Valley,” explains Xavier Dupont, DVG president of the community of municipalities Touraine West Val de Loire.

The law provided for a period of ten years during which the State must continue to maintain its dikes and ensure compliance work before the transfer. This is the case of Saint-Malo, where the State has rehabilitated several hundred 200-year-old breakwaters which protect the Sillon dike.

But in general, "very few investments have been made in recent years", underlines Oriane Cebile, of the Intercommunalités de France association.

A certain number of elected officials could even recover structures "in very poor condition", warns the Association of Mayors of France (AMF), recalling that the Loire dikes, strategic for the protection of populations, do not all withstand floods centennials.

The situation is not without concern for elected officials. “The State remains the owner but entrusts us with all the responsibilities of the owner, all without additional financial means, including criminal liability if it is established that a flood is the consequence of poor maintenance of the dikes,” regrets Xavier Dupont.

Because the State considers that this is not a transfer of "skills" but a simple "transfer of management" therefore not giving rise to any financial compensation or transfer of personnel.

100% in flood zone

To finance the work, the law refers to the "Gemapi" tax, integrated into the property tax, which intermunicipalities can levy since 2018. But for elected officials, this tax limited to 40 euros per inhabitant is clearly not sized to cover significant investments, strengthening the bases of dikes, monitoring water attacks, etc.

However, some dikes measure up to 8 meters high and extend for tens of kilometers. Formerly designed to enable navigation, today they protect "populations, activity zones, businesses", underlines Nicolas Camphuis, co-director of the European Center for Flood Risk Prevention (Cepri).

“The city of Tours, for example, is almost 100% in a flood zone, as is Saint-Pierre-des-Corps, with its railway junction between the Cher and the Loire,” he notes.

The level of the Loire is certainly historically low. “But with climate change, we could have sudden precipitation, and it could flood quite quickly,” says Xavier Dupont.

Further south, the president of Carcassonne Agglo Régis Banquet fears violent storms, "more frequent today". “We no longer ask ourselves the question of whether it will happen but when”, recognizes the elected socialist, “ready to take the transfer” but “with the means that go with it”.

Others consider the burden too heavy for intermunicipalities located on major rivers, such as in Marmande, where the Garonne passes. “The Garonne watershed represents an area of ​​55.000 km2, and during the last flood in 2021, Marmande saw more than 6.000 m3 of water pass per second”, remembers Jacques Bilirit (PS), president of Val de Garonne Agglomeration.

Another problem and not the least, the State has not recorded the location or the state of solidity of all its dikes. “There are pieces of state dikes wandering around everywhere, in Dunkirk or in Savoie, which means that a certain number of intermunicipalities will discover this automatic transfer on January 28, 2024,” fears the AMF.